1 //===-- CodeGen/AsmPrinter/ARMException.cpp - ARM EHABI Exception Impl ----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains support for writing DWARF exception info into asm files.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "DwarfException.h"
14 #include "llvm/ADT/Twine.h"
15 #include "llvm/CodeGen/AsmPrinter.h"
16 #include "llvm/CodeGen/MachineFunction.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/Mangler.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/MC/MCAsmInfo.h"
21 #include "llvm/MC/MCExpr.h"
22 #include "llvm/MC/MCSection.h"
23 #include "llvm/MC/MCStreamer.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/Support/FormattedStream.h"
26 #include "llvm/Target/TargetOptions.h"
27 using namespace llvm;
28 
29 ARMException::ARMException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
30 
31 ARMException::~ARMException() {}
32 
33 ARMTargetStreamer &ARMException::getTargetStreamer() {
34   MCTargetStreamer &TS = *Asm->OutStreamer->getTargetStreamer();
35   return static_cast<ARMTargetStreamer &>(TS);
36 }
37 
38 void ARMException::beginFunction(const MachineFunction *MF) {
39   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
40     getTargetStreamer().emitFnStart();
41   // See if we need call frame info.
42   AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
43   assert(MoveType != AsmPrinter::CFI_M_EH &&
44          "non-EH CFI not yet supported in prologue with EHABI lowering");
45 
46   if (MoveType == AsmPrinter::CFI_M_Debug) {
47     if (!hasEmittedCFISections) {
48       if (Asm->needsOnlyDebugCFIMoves())
49         Asm->OutStreamer->EmitCFISections(false, true);
50       hasEmittedCFISections = true;
51     }
52 
53     shouldEmitCFI = true;
54     Asm->OutStreamer->EmitCFIStartProc(false);
55   }
56 }
57 
58 /// endFunction - Gather and emit post-function exception information.
59 ///
60 void ARMException::endFunction(const MachineFunction *MF) {
61   ARMTargetStreamer &ATS = getTargetStreamer();
62   const Function &F = MF->getFunction();
63   const Function *Per = nullptr;
64   if (F.hasPersonalityFn())
65     Per = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
66   bool forceEmitPersonality =
67     F.hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
68     F.needsUnwindTableEntry();
69   bool shouldEmitPersonality = forceEmitPersonality ||
70     !MF->getLandingPads().empty();
71   if (!Asm->MF->getFunction().needsUnwindTableEntry() &&
72       !shouldEmitPersonality)
73     ATS.emitCantUnwind();
74   else if (shouldEmitPersonality) {
75     // Emit references to personality.
76     if (Per) {
77       MCSymbol *PerSym = Asm->getSymbol(Per);
78       Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global);
79       ATS.emitPersonality(PerSym);
80     }
81 
82     // Emit .handlerdata directive.
83     ATS.emitHandlerData();
84 
85     // Emit actual exception table
86     emitExceptionTable();
87   }
88 
89   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
90     ATS.emitFnEnd();
91 }
92 
93 void ARMException::emitTypeInfos(unsigned TTypeEncoding,
94                                  MCSymbol *TTBaseLabel) {
95   const MachineFunction *MF = Asm->MF;
96   const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
97   const std::vector<unsigned> &FilterIds = MF->getFilterIds();
98 
99   bool VerboseAsm = Asm->OutStreamer->isVerboseAsm();
100 
101   int Entry = 0;
102   // Emit the Catch TypeInfos.
103   if (VerboseAsm && !TypeInfos.empty()) {
104     Asm->OutStreamer->AddComment(">> Catch TypeInfos <<");
105     Asm->OutStreamer->AddBlankLine();
106     Entry = TypeInfos.size();
107   }
108 
109   for (const GlobalValue *GV : reverse(TypeInfos)) {
110     if (VerboseAsm)
111       Asm->OutStreamer->AddComment("TypeInfo " + Twine(Entry--));
112     Asm->EmitTTypeReference(GV, TTypeEncoding);
113   }
114 
115   Asm->OutStreamer->EmitLabel(TTBaseLabel);
116 
117   // Emit the Exception Specifications.
118   if (VerboseAsm && !FilterIds.empty()) {
119     Asm->OutStreamer->AddComment(">> Filter TypeInfos <<");
120     Asm->OutStreamer->AddBlankLine();
121     Entry = 0;
122   }
123   for (std::vector<unsigned>::const_iterator
124          I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
125     unsigned TypeID = *I;
126     if (VerboseAsm) {
127       --Entry;
128       if (TypeID != 0)
129         Asm->OutStreamer->AddComment("FilterInfo " + Twine(Entry));
130     }
131 
132     Asm->EmitTTypeReference((TypeID == 0 ? nullptr : TypeInfos[TypeID - 1]),
133                             TTypeEncoding);
134   }
135 }
136